Remote controlled (RC) model airplanes have been a favorite of hobbyists for many years. Initially, in the early years of RC aircraft popularity, the radio controls were relatively expensive and required a larger model aircraft to carry the weight of a battery, receiver and the various servos to provide the remote controllability for the model aircraft. These aircraft were typically custom built of lightweight materials, such as balsa wood, by the hobbyist. Consequently, these RC models represented a significant investment of the hobbyist's time, effort, experience, and money. Further, because of this investment, the hobbyist needed a high degree of expertise in flying the model aircraft to conduct safe operations and prevent crashes. In the event of a crash, most models would incur significant structural damage requiring extensive repairs or even total rebuilding of the model. For these reasons, participation in this hobby was self-restricting to the few who could make the required investments of time and money.
As innovations in the electronics industry resulted in smaller and less inexpensive electronics, the cost and size of radio control units were also reduced allowing more hobbyists to be able to afford these items. Further, these advances also result in reductions in weight of the battery, receiver and servos, which benefits could then be realized in smaller and lighter model airframes. This meant that the building of the airframes could become simpler and no longer requiring the degree of modeling expertise previously required. Simplicity of construction and durability of the airframes were further enhanced with the advent of more modern materials, such as synthetic plastics, foams, and composites, such that the airframes could withstand crashes with minimal or even no damage.
These RC models were still based upon the restraints of airplane aerodynamics meaning they still needed a runway for takeoffs and landings. While the length of the required runways (even if only a relatively short grassy strip) vary according to the size of the RC model, the requirement often relegated the flying of these models to designated areas other than a typical back yard. Model helicopters, like the full-scale real life aircraft they are based upon, do not require runways and can be operated from small isolated areas. However, a helicopter with a single main rotor requires a tail rotor, whether full scale or model, also requires a tail rotor to counter the rotational in flight moment or torque of the main rotor. Flying a helicopter having a main rotor and a tail rotor requires a level of expertise that is significantly greater than required for a fixed wing aircraft, and therefore limits the number of hobbyists that can enjoy this activity.
The complexity of remotely flying a model helicopter has at least been partially solved by small prefabricated models that are battery operated and employ two main counter-rotating rotors. The counter-rotation of the two rotors results in equal and counteracting moments or torques applied to the vehicle and therefore eliminating one of the complexities of piloting a helicopter-like vertical take-off and landing model. These models typically have another limiting characteristic in that the form factor of the structure and the necessary placement of the rotors above the vehicle structure result in a tendency for the vehicle to be prone to tipping on one or the other side when landing. In the event of this occurring, the vehicle must be righted in order for further operations and thus requires the operator or other individual to walk to the remote location of the vehicle and right it so that the operator can again command the vehicle to take off.
Therefore, a self-righting structural frame and corresponding vertical take-off vehicle design is needed to permit remote operation of a helicopter-like RC model without the need to walk to a landing site to right the vehicle in the event the previous landing results in a vehicle orientation other than upright.